This invention relates to a colour photographic material comprising a transparent support, at least one blue-sensitive, predominantly yellow-coupling silver halide emulsion layer, at least one green-sensitive, predominantly magenta-coupling silver halide emulsion layer (PP-1) and at least one red-sensitive, predominantly cyan-coupling silver halide emulsion layer (BG-1).
It is known from EP 434 044 that the production of a coloured material which has its maximum red sensitivity within the range from 595 to 625 nm and its maximum green sensitivity within the range from 530 to 560 nm is advantageous for high colour saturation and for good reproduction of certain colours.
It is known from U.S. Pat. No. 5,169,746 that certain colours are reproduced well if the red sensitivity at 650 nm is at least 50 % less than the maximum red sensitivity, if no magenta-coloured cyan masking coupler is used at the same time.
U. S. Pat. No. 5,723,280 discloses that a high sensitivity can be attained with certain spectral sensitisers despite their maximum red sensitivity being situated at less than 640 nm. These spectral sensitisers are trimethine cyanine dyes comprising a substituted benzoxazole and a substituted benzthiazole or benzselenazole radical, which contain a condensed phenyl radical and which comprise a 2-sulphoethyl group on a nitrogen atom. According to the teaching of U.S. Pat. No. 5,853,968, similar sensitisers in combination with other red sensitisers also result in improved colour reproduction and in better bleachability.
It is also mentioned in the above patent specifications that the claimed materials can contain filter layers comprising magenta dyes for example. Advantageous inter-actions or a preferred arrangement within the material are not disclosed in connection with these additives, however.
The starting point for each of the aforementioned patent specifications was the discrepancy, which has long been known, between the red sensitivity of the human eye and the red sensitivity of colour films, which is shifted bathochromically with respect to the human eye. The teaching which is emphasised therein is to effect a hypsochromatic shift of the sensitisation to red as far as possible until it corresponds to the red sensitivity distribution of the human eye.
However, because the processing of an exposed film to form a coloured image proceeds differently from the colour processing phenomena in the brain, an accurate adjustment of the sensitisation in the film to match the spectral sensitivity distribution of the human eye is not the solution to all colour reproduction problems. In particular, the colour adaptation of the eye cannot be adjusted thus, which gives rise to more or less pronounced colour casts depending on the ambient illumination. Thus the materials according to the prior art exhibit too high a level of colour when standard daylight is replaced by light of a different colour temperature. In particular, these prior art materials are unsatisfactory for taking photographs in artificial light from fluorescent lamps.
Another disadvantage of these known materials is their sensitivity to short wave red light, which is still unsatisfactory.
Moreover, the colour reproduction according to the prior art is still unsatisfactory for certain colours of flowers, e.g. delphinium, and for some textile colours. All colours are affected which exhibit a significant absorption in the long wave red region or in the infrared region.
Furthermore, no success has been achieved with these prior art materials in fulfilling the severe demands imposed on the stability of modem colour photographic silver halide materials. For the production of all-round colour films in particular, which should be capable of being used worldwide, the stability under humid climatic conditions is still unsatisfactory.
The underlying object of the present invention was thus to identify a colour photo-graphic silver halide material with a high sensitivity to light, which in addition to its colour reproduction in standard light also gives good results in other types of illumination, particularly in the artificial light from fluorescent lamps, which reproduces colours such as that of the delphinium without distortion, and which exhibits high stability on storage under humid climatic conditions.
Surprisingly, it has now been found that this object can be achieved if the spectral sensitivity distribution of the cyan layer in a colour photographic material is adjusted so that the sensitivity maximum is situated in the vicinity of 620 nm, and the sensitivity in the longer wavelength region first of all falls only slightly up to 640 nm and then falls steeply up to 680 nm. This condition is fulfilled by a maximum of unsymmetrical width or preferably by a secondary maximum or by a pronounced shoulder in the spectral sensitivity distribution, wherein the wider part of the red sensitivity curve, the secondary maximum, or the shoulder, is shifted batho-chromatically in relation to the maximum. Expressed numerically, the sensitivity at 640 nm has to be less by a certain extent than the maximum sensitivity which is shifted towards the short wave region, and the sensitivity at 680 nm has to be less by a minimum extent than the maximum sensitivity. This type of red sensitivity distribution differs considerably from the types of red sensitisation which has been used hitherto in photographic materials and from those which have been described hitherto. Surprisingly, the sensitisation according to the invention which was defined above, and which differs considerably from the sensitivity distribution of the human eye, results in better reproduction in artificial light than when the teaching of the prior art is followed.
The present invention therefore relates to a colour photographic material comprising a transparent support, at least one blue-sensitive, predominantly yellow-coupling silver halide emulsion layer, at least one green-sensitive, predominantly magenta-coupling silver halide emulsion layer (PP-1) and at least one red-sensitive, predominantly cyan-coupling silver halide emulsion layer (BG-1), characterised in that the spectral sensitivity distribution of BG-1 is characterised in that
605xe2x89xa6xcexmaxxe2x89xa6630 nm, 
0.1xe2x89xa6xcex94lgE640xe2x89xa60.6 and 
1.8xe2x89xa6xcex94lgE680, 
wherein xcexmax represents the wavelength at which the maximum sensitivity occurs, xcex94lgE640 represents the difference of the logarithmic sensitivity at xcexmax minus the logarithmic sensitivity at 640 nm, and xcex94lgE680 represents the difference of the logarithmic sensitivity at xcexmax minus the logarithmic sensitivity at 680 nm, and the sensitivities are determined after exposure and processing of the material at a cyan colour density which is formed by coupling with developer oxidation product and which is 0.5 above the minimum density.
The logarithmic spectral sensitivities are obtained from the spectrogram of the photographic material by plotting logarithmic sensitivity against wavelength, wherein it has proved most useful to measure the sensitivities at a density of 0.5 greater than DMin. For this purpose, the test material is processed according to standards or by methods provided for the material.
The strong dependence of the reproduction in artificial light on the shape of the spectrum was particularly surprising. If a departure is made from the aforementioned ranges for xcexmax and for xcex94lgE640, a significant green cast is obtained for exposures made in the light from fluorescent lamps. Particularly good results, even with regard to delphinium reproduction, are achieved if
610xe2x89xa6xcexmaxxe2x89xa6625 nm,
0.2xe2x89xa6xcex94lgE640xe2x89xa60.5 and
2.0xe2x89xa6xcex94lgE680.
PP-1 is preferably further from the support than is BG-1, and at least one green-absorbing dye is contained in BG-1 or in a layer which is situated between PP-1 and BG-1. The at least one green-absorbing dye is most preferably contained in a layer which is situated between PP-1 and BG-1. Even though the green-absorbing dye, the absorption of which always has a certain half-width value, also absorbs part of the light in this arrangement to which the short wave red-sensitised BG-1 layer is sensitive, it has surprisingly been found that there is no significant loss in sensitivity due to a dye such as this, despite the aforementioned layer arrangement. It was also surprising that the colour reproduction in artificial light illumination, particularly in the light from a fluorescent tube, was sometimes further improved, or at least remained just as good, even though, due to the dye, the spectral sensitisation of the film exhibited a clear separation between the red- and green-sensitive layers and thus differed even more significantly from the human eye, which is characterised by a broad overlap between its red- and green-sensitive sensors. Instead, it is possible to achieve a more strongly differentiated reproduction of orange, yellow/orange and yellow/green shades due to the reduced overlap between the spectral sensitivities of BG-1 and PP-1, which results from the use according to the invention of the green-absorbing dye.
The advantages obtained are particularly pronounced, and are surprisingly associated with improved stability under humid conditions, if the at least one green-absorbing dye is the aluminium-coloured lake of aurinetricarboxylic acid.
In order to achieve the kind of red sensitisation according to the invention, it has proved to be advantageous to use a mixture of at least two red sensitisers in BG-1. It is particularly advantageous if just two sensitisers are used simultaneously. It is preferable to use 1xc2x710xe2x88x924 to 2xc2x710xe2x88x923, most preferably 3xc2x710xe2x88x924 to 1,2xc2x710xe2x88x923 mol sensitisers per mol silver halide, wherein each known variant of the method of addition is suitable. Spectral sensitisation is preferably effected over a period of time ranging from just before chemical sensitisation until the production of the cast melt, most preferably directly before chemical sensitisation. The sensitisers are advantageously added as a solution or as a dispersion.
In one embodiment of the invention, which is particularly advantageous for the sensitivity, at least one dye of formula I and at least one dye of formula II are contained in BG-1:
wherein the radicals R1 to R6 denote hydrogen, a halogen, or a cyano, methyl, tri-fluoromethyl, methoxy, aryl or hetaryl radical, or
R1 together with R2, or R2 together with R3 and/or R4 together with R5, or R5 together with R6, denote the remaining members of a substituted or unsubstituted condensed-on benzene or naphthalene ring system, and the radicals R1 to R6, which are not part of a ring system, denote hydrogen, a halogen, or a cyano, methyl, trifluoromethyl, methoxy, aryl or hetaryl radical,
R7, R8 denote an alkyl Y1O3S-alkylene, Y1O2C-alkylene, alkylene-SO2xe2x80x94NY1xe2x80x94SO2-alkyl, alkylene-SO2xe2x80x94NY1xe2x80x94CO2-alkyl, alkylene-COxe2x80x94NY1xe2x80x94SO2-alkyl or alkylene-COxe2x80x94NY1xe2x80x94CO-alkyl radical, wherein the alkyl and alkylene can be further substituted,
Y1 denotes hydrogen or a negative charge,
R9 denotes hydrogen or a methyl or ethyl radical, and
M1 optionally denotes a counterion for charge compensation, and 
wherein
X1 denotes sulphur or selenium,
X2 denotes oxygen or Nxe2x80x94R10. 
R10 denotes an alkyl, Y1O3S-alkylene or Y1O2C-alkylene, wherein the alkyl and alkylene can be further substituted and comprise 1 to 6 C atoms,
the radicals R11 to R16 denote hydrogen, a halogen, or a cyano, methyl, trifluoro-methyl, methoxy, aryl or hetaryl radical, or
R11 together with R12, or R12 together with R13 and/or R14 together with R15, or R15 together with R16, denote the remaining members of a substituted or unsubstituted condensed-on benzene or naphthalene ring system and the radicals R11 to R16, which are not part of a ring system, denote hydrogen, a halogen, or a cyano, methyl, trifluoromethyl, methoxy, aryl or hetaryl radical,
R17, R18 denote an alkyl Y1O3S-alkylene, Y1O2C-alkylene, alkylene-SO2xe2x80x94NY1xe2x80x94SO2-alkyl, alkylene-SO2xe2x80x94NY1xe2x80x94CO-alkyl, alkylene-COxe2x80x94NY1xe2x80x94SO2-alkyl or alkylene-COxe2x80x94NY1xe2x80x94CO-alkyl radical, wherein the alkyl and alkylene can be further substituted,
R19 denotes hydrogen or a methyl or ethyl radical, and
M2 optionally denotes a counterion for charge compensation.
In a test of spectral sensitisers, some particularly preferably structural features with regard to spectral sensitivity were identified, and are listed below.
It is advantageous if the alkyl and alkylene groups of R7, R8, R17 and R18 contain 1 to 6 C atoms, and it is particularly advantageous if they contain 3 to 6 C atoms.
In a further advantageous embodiment, at least one of the substituents R1 to R6 denotes chlorine. It is particularly preferred if R2 and R5 denote chlorine and R1, R3, R4 and R6 denote hydrogen.
It is preferable if X2 is oxygen. In one particularly preferred embodiment, X1 denotes selenium. The best results are obtained when X1 is selenium and X2 is oxygen.
In one preferred embodiment, R12 together with R13 denotes the remaining members of a substituted or unsubstituted condensed-on benzene ring system, and R11 denotes hydrogen and/or R14 together with R15 denotes the remaining members of a substituted or unsubstituted condensed-on benzene ring system and R16 denotes hydrogen.
It is also advantageous if
R15 denotes chlorine, cyano, methyl, trifluoromethyl, phenyl, thienyl, benzthienyl or pyrrolyl, and
R16 denotes H, chlorine or methyl.
In another preferred embodiment,
R11 denotes H, methyl or methoxy, and
R12 denotes chlorine, methyl or methoxy.
Particularly suitable compounds of formulae I und II are listed below: 
If more than one red sensitiser is used, the form of the spectrogram according to the invention can be altered via the mixture ratio of the sensitisers. If a long wave sensitiser and a short wave sensitiser corresponding to formulae I and II are used, the preferred molar mixture ratios range from 1:2 to 1:9, expressed in each case as parts of sensitiser of formula I to parts of sensitiser of formula II. Mixture ratios ranging from 1:2.5 to 1:6 are particularly preferred. The desired result can be obtained using any sequence of addition. It is particularly preferred if the sensitiser of formula II is added first, followed by the sensitiser of formula I.
It is advantageous if BG-1 contains at least one silver bromide-iodide emulsion or silver bromide-chloride-iodide emulsion which has an iodide content of 0.5 to 40 mol % and a chloride content of 0 to 10 mol %, and at least 50% of which, with respect to the projected area, consists of tabular grains with an aspect ratio of at least 4, particularly if the tabular grains have a structured arrangement comprising a core, an inner zone and an outer zone and the inner zone contains at least one iodide-rich crystal zone which has an iodide content of 2 to 45 mol % and which with respect to the silver makes up 10 to 70 mol % the crystals and has a higher iodide content than the core and the outer zone.
In a further preferred embodiment, the invention relates to a colour photographic material which contains at least two blue-sensitive, predominantly yellow-coupling silver halide emulsion layers, at least two green-sensitive, predominantly magenta-coupling silver halide emulsion layers (PP-1 and PP-2) and at least two red-sensitive, predominantly cyan-coupling silver halide emulsion layers (BG-1 and BG-2), each of which has a different sensitivity, and that the spectral sensitivity distribution of BG-2 is also characterised in that
605xe2x89xa6xcexmaxxe2x89xa6630 nm,
0.1xe2x89xa6xcex94lgE640xe2x89xa60.6, and
1.8xe2x89xa6xcex94lgE680.
It has surprisingly been found that by using the same type of spectral sensitisation according to the invention in a material which comprises two layers in each colour stack, the advantages of the invention compared with a corresponding single layer material are considerably increased.
The colour photographic material most preferably contains at least two blue-sensitive, predominantly yellow-coupling silver halide emulsion layers, at least three green-sensitive, predominantly magenta-coupling silver halide emulsion layers (PP-1, PP-2 and PP-3) and at least three red-sensitive, predominantly cyan-coupling silver halide emulsion layers (BG-1, BG-2 and BG-3), each with a different sensitivity, wherein the spectral sensitivity distribution of BG-1, BG-2 and BG-3 is characterised in that
605xe2x89xa6xcexmaxxe2x89xa6630 nm,
0.1xe2x89xa6xcex94lgE640xe2x89xa60.6, and
1.8xe2x89xa6xcex94lgE680.
Surprisingly, by using the same type of spectral sensitisation according to the invention in a material which comprises three layers in the magenta and cyan colour stacks at least, the advantages of the invention compared with a corresponding two-layer material are increased considerably further.
Examples of colour photographic materials include colour negative films, colour reversal films, colour positive films, colour photographic paper, colour reversal photographic paper, and colour-sensitive materials for the colour diffusion transfer process or the silver halide bleaching process. Reviews are given in Research Disclosure 37038 (1995) and in Research Disclosure 38957 (1996).
Photographic materials consist of a support on which at least one light-sensitive silver halide emulsion layer is deposited. Thin films and foils are particularly suitable as supports. A review of support materials and of the auxiliary layers which are deposited on the front and back thereof is given in Research Disclosure 37254, Part 1 (1995), page 285 and in Research Disclosure 38957, Part XV (1996), page 627.
Color photographic materials usually contain at least one red-sensitive, at least one green-sensitive and at least one blue-sensitive silver halide emulsion layer, and optionally contain intermediate layers and protective layers also.
Depending on the type of photographic material, these layers may be arranged differently. This will be illustrated for the most important products:
Color photographic films such as colour negative films and colour reversal films comprise, in the following sequence on their support: 2 or 3 red-sensitive, cyan-coupling silver halide emulsion layers, 2 or 3 green-sensitive, magenta coupling silver halide emulsion layers, and 2 or 3 blue-sensitive, yellow-coupling silver halide emulsion layers. The layers of identical spectral sensitivity differ as regards their photographic speed, wherein the less sensitive partial layers are generally disposed nearer the support than are the more highly sensitive partial layers.
A yellow filter layer is usually provided between the green-sensitive and blue-sensitive layers, to prevent blue light from reaching the layers underneath.
The options for different layer arrangements and their effects on photographic properties are described in J. Inf. Rec. Mats., 1994, Vol. 22, pages 183-193, and in Research Disclosure 38957, Part XI (1996), page 624.
Color photographic paper, which as a rule is less sensitive to light than is colour photographic film, usually comprises the following layers on the support, in the following sequence: a blue-sensitive, yellow-coupling silver halide emulsion layer, a green-sensitive, magenta coupling silver halide emulsion layer, and a red-sensitive, cyan-coupling silver halide emulsion layer. The yellow filter layer can be omitted.
Departures from the number and arrangement of the light-sensitive layers may be effected in order to achieve defined results. For example, all the high-sensitivity layers may be combined to form a layer stack and all the low-sensitivity layers may be combined to form another layer stack in a photographic film, in order to increase the sensitivity (DE 25 30 645).
The essential constituents of the photographic emulsion layer are binders, the silver halide grains and colour couplers.
Information on suitable binders is given in Research Disclosure 37254, Part 2 (1995), page 286, and in Research Disclosure 38957, Part IIa (1996), page 598.
Information on suitable silver halide emulsions, their production, ripening, stabilisation and spectral sensitisation, including suitable spectral sensitisers, is given in Research Disclosure 37254, Part 3 (1995), page 286, in Research Disclosure 37038, Part XV (1995), page 89, and in Research Disclosure 38957, Part VA (1996), page 603.
Photographic materials which exhibit camera-sensitivity usually contain silver bromide-iodide emulsions, which may also optionally contain small proportions of silver chloride. Photographic copier materials contain either silver chloride-bromide emulsions comprising up to 80 mole % AgBr, or silver chloride-bromide emulsions comprising more than 95 mole % AgCl.
Information on colour couplers is to be found in Research Disclosure 37254, Part 4 (1995), page 288, in Research Disclosure 37038, Part II (1995), page 80, and in Research Disclosure 38957, Part XB (1996), page 616. The maximum absorption of the dyes formed from the couplers and from the colour developer oxidation product preferably falls within the following ranges: yellow couplers 430 to 460 nm, magenta couplers 540 to 560 nm, cyan couplers 630 to 700 nm.
In order to improve sensitivity, granularity, sharpness and colour separation, compounds are frequently used in colour photographic films which on reaction with the developer oxidation product release compounds which are photographically active, e.g. DIR couplers, which release a development inhibitor.
Information on compounds such as these, particularly couplers, is to be found in Research Disclosure 37254, Part 5 (1995), page 290, in Research Disclosure 37038, Part XIV (1995), page 86, and in Research Disclosure 38957, Part X.C (1996), page 618.
The colour couplers, which are mostly hydrophobic, and other hydrophobic constituents of the layers also, are usually dissolved or dispersed in high-boiling organic solvents. These solutions or dispersions are then emulsified in an aqueous binder solution (usually a gelatine solution), and after the layers have been dried are present as fine droplets (0.05 to 0.8 xcexcm diameter) in the layers.
Suitable high-boiling organic solvents, methods of introduction into the layers of a photographic material, and other methods of introducing chemical compounds into photographic layers, are described in Research Disclosure 37254, Part 6 (1995), page 292.
The light-insensitive intermediate layers which are generally disposed between layers of different spectral sensitivity may contain media which prevent the unwanted diffusion of developer oxidation products from one light-sensitive layer into another light-sensitive layer which has a different spectral sensitivity.
Suitable compounds (white couplers, scavengers or DOP scavengers) are described in Research Disclosure 37254, Part 7 (1995), page 292, in Research Disclosure 37038, Part III (1995), page 84, and in Research Disclosure 38957, Part X.D (1996), page 621 et seq.
The photographic material may additionally contain compounds which absorb TV light, brighteners, spacers, filter dyes, formalin scavengers, light stabilisers, anti-oxidants, DMin dyes, plasticisers (latices), biocides, additives for improving the dye-, coupler- and white stability and for reducing colour fogging and for reducing yellowing, and other substances. Suitable compounds are given in Research Disclosure 37254, Part 8 (1995), page 292, in Research Disclosure 37038, Parts IV, V, VI, VII, X, XI and XIII (1995), pages 84 et seq., and in Research Disclosure 38957, Parts VI, VIII, IX, X (1996), pages 607, 610 et seq.
The layers of colour photographic materials are usually hardened, i.e. the binder used, preferably gelatine, is crosslinked by suitable chemical methods.
Suitable hardener substances are described in Research Disclosure 37254, Part 9 (1995), page 294, in Research Disclosure 37038, Part XII (1995), page 86, and in Research Disclosure 38957, Part II.B (1996), page 599.
After image-by-image exposure, colour photographic materials are processed by different methods corresponding to their character. Details on the procedures used and the chemicals required therefor are published in Research Disclosure 37254, Part 10 (1995), page 294, in Research Disclosure 37038, Parts XVI to XXIII (1995), page 95 et seq., and in Research Disclosure 38957, Parts XVIII, XIX, XX (1996) page 630 et seq., together with examples of materials.